Timed circuit breaker mechanism



y 939 1. E. MCCABE 2,158,515

TIMED CIRCUIT BREAKER MECHANISM Original Filed March 20, 1935 3 Sheets-Sheet l I 5 i I 1 r I 5 I ill INVENTOR. [RR E. N E/15E BY f M ATTORNEY.

May 16, 1939. l. E. M CABE TIMED CIRCUIT BREAKER MECHANISM Original Filed March 20, 1933 3 Shegts-Sheet 2 INVENTOR. [Ff/i f. MC/IBE ATTORNEY.

I E. M CABE May 16, 1939.

TIMED CIRCUIT BREAKER MECHANISM Original Filed March 20, 1933 5 Sheets-Sheet 5 ETWff/Y FLAME 54/1 [/85 4/70 M070)? 56 117 DOW/7 5y 5/7/27) Mflf/A/l/JM 0 0 0 0 n m m 1 INVENTOR.

1/7/1 E. MLWBE BY M ATTORNEY.

Patented May 16, 1939 2,158,515 'rmmn omcorr panama MECHANISM Ira n. McCabe, Chicago, 111.

Original application March 20, 1933, Serial a...

661,759, now Patent No. 2,024,697, dated December 17, 1935.

Divided and this application November 14, 1935, Serial No. 49,777

5 Claims. (Cl. 175- 375) It is an object of this invention to combine a thermally operated safety switch mechanism and a transformer repulsion relay operated switch in 15 such a manner as to insure operation of the safety switch at any and all times it may be required to operate including such times in which the relay circuit remains closed regardless. of minimum line voltages. It is another object of this invention to provide a relay of the movable coil transformer type for opening and closing the" controlled circuit, and

employing the secondary circuit of the relay as the control circuit for the controlled circuit by including therein a remote control and a safety switch release mechanism. The sewndary circuit thus established offers a substantially constant period for allowing the mechanism to go into normal running operation before causing a shut down if that time exceeds the normal time required for such operation to be obtained.

It is a still further object of this invention to provide means for manually stopping the operation of the mechanism andmeans for manually resetting the control mechanism.

With these and other objects in view, reference is made to the accompanying sheets of drawings illustrating a preferred embodiment of this invention, with the understanding that minor detail changes may be made therein without departing from the scope thereof.

Figure 1 is a diagrammatical view illustratinz the control elements of an embodiment of this invention as applied to an intermittent ignition electrically operated fluid fuel burner mechanism with a wiring diagram connecting the parts thereof with the switches employed in the improved control. i

Figure 2 is a view in front elevation in this.

improved control with the cover removed, and also the plate and safety switch mounted thereon removed, said plate being indicated by dot and dash lines, with the parts illustrated in the cold or idle position.

a Figure 31s asimilar viewofsaidpartsinthe position assumed when the burner mechanism is running or in normal operation with parts omitted.

Figure 4 is a fragmentary detail view in front elevation of the relay and switch operated thereby shown in Figure 2.

Figure 5 is a view in end elevation of the relay shown in Figure 4.

Figure 6 is a view in end elevation, partly in section,'. illustrating the ignition and shunt switches and the stack safety mechanism connected therewith.

Figure '7 is a top plan view partly in section of the ignition switch as shown in Figure 6, and i1- lustrating the operating parts thereof.

Figure 8 is a view in front elevation of the plate carrying the safety switch and operating mechanism thereof, with the switch carrying bracket broken away and the said switch removed.

Figure 9 is a view in end elevation of Figure 8 with the carrying plate shown in section.

FigurelO is a fragmentary detailed view in front elevation, partly in section, of the safety switch carrying bracket.

Figure 11 is a chart plotted to illustrate graphically a portion of the specification.

As an embodiment of this invention, the improved timed circuit breaker mechanism is illustrated in connection with an electrically operated and controlled fluid fuel burner mechanism in which the control mechanism is mounted upon a panel I, as shown in Figure 2, and includes a stack safety mechanism as disclosed in this applicant's prior Patent No. 1,762,183, dated June 10, 1930, having an actuating shaft 2 operated by the expansion of the thermal coil 3 to rotate the shunt switch carrying plate 4, shown in Figure 6. The shunt switch 5 is carried upon the plate 4 in the idle or cold position, as shown in Figure 2, is open as shown in the wiring diagram in Figure 1. The relay operated motor switch 6 is interposed in the commercial circuit between the source of electricity and the motor M. The incoming commercial circuit passes preferably through the boiler control B of commercial construction, and a safety switch I, hereinafter described, through the motor switch 6, when closed, through the motor M and back to the other line of the commercial circuit. The motor switch 6 is actuated by a relay of the constant current repulsion type, including a stationary primary coil I connected. in series with the safety switch across the-line and a secondary movable coil- 9 connected in series with the room thermostat T and the shunt switch I. The secondary coil I is wound about one vertical leg of a rectangular core and connected by a bracket 9a (Figure 3) to the under side of the movable secondary coil 9, so that when the secondary circuit is closed through the room thermostat T, the relay is energized and the secondary coil 9 is repelled from the stationary primary coil 8 thereby closing the circuit to the motor M through the motor switch 6 and this circuit will remain closed during the normal operation of the burner, that is, as long as the room thermostat T calls for heat.

The safety switch I is mounted preferably upon a bracket I2 rotatably carried upon a pin I? mounted between plates 20a and 20b carried upon a base plate P, as shown in Figures 8 and 9, which base plate is secured preferably between the laminations of the rectangular core l0, as shown in Figures 4 and 5. That portion of the bracket l2 which is mounted upon the pin it is provided with spaced apart stops id and i 5 adapted to engage a stud 5 when the safety switch has been rotated to opened or closed position. A depending holding arm H is mounted upon the bracket i2 adapted, when the switch has been rotated to its normal closed position with the stop it in engagement with the stud l6, to engage a pin Hi carried upon the free end of a bi-metallic thermostatic member M to hold the safety switch in closed position. It is preferable to construct the holding arm ll of the same material .as the arm is, so that they will both react to atmospheric (ambient) temperature changes in the same manner without becoming disengaged. This thermostatic strip 89 is passed about a heat coil 20 and the other end secured to the plate 200 mounted upon the base plate P. The heat coil 22 is connected in series in the secondary circuit between the movable coil 9 and a room thermostat T, so that if the secondary circuit continues to pass through the said heat coil, the heat therefrom will cause the bi-metallic' strip is to deform to carry' the pin l8 out of contact with the arm ii. The safety switch 1 being mounted upon the bracket l2 with the majority of its weight upon the same side of the pivot as the arm ll will cause the safety switch to open the circuit to the motor. The shunt switch 5 is connected across the line in the secondary circuit on opposite sides of the heating element 20 and when the burner is idle is normally in the open position, so that when the room thermostat calls for heat the secondary circuit is established through the heat coil and the establishment of the secondary circuit energizes the repulsion relay to close the motor circuit.

An ignition switch 2|, normally closed when the burner is idle, is connected in series with a commercial ignition transformer I, the relay switch 6 and safety switch 7 across the commercial line, so that when the room thermostat calls for heat the secondary circuit will be energized to close the motor circuit through switches 6 and i and close the ignition circuit through the switch 2 i.

In the event that combustion occurs the thermostatic element 3 of the stack control will impart rotation to the shunt switch 5 to close the secondary circuit therethrough and shunt out the heating element 20 of. the safety switch 1, whereby the'motor circuit is maintained. In the event that combustion fails to occur the thermostatic element 3 remains inactive and the secondary current continues to pass through the resistance heating element 20 causing the arm I9 to deform and release the safety switch I to open the motor circuit, likewise, in the event of flame failure during normal operation, the thermostatic element cools and returns to normal, returning the shunt switch 5 to the open position so that the heating element 20 is energized to release the safety switch I to open the motor circuit.

In order that the ignition switch 2| may be opened after ignition is established and locked in the open position until the room thermostat opens the secondary circuit, the ignition switch is carried upon a plate 22 pivotally mounted between spaced apart plates 22a and 2217 (Figures 6 and 7) mounted upon the panel .I by posts 23 to clear the outside of the stack safety mechanism and shunt switch 5. The ignition switch 2| is mounted upon a right angular outward extension 24 of the carrying plate 22, so that the weight of the switch is on one side of its pivot 25 and the extremity of the mounting farthest from the pivot is provided with an actuator latch 26 which extends over the shunt switch 5, whereby when the parts are in idle position, as shown in Figure 2, the shunt switch 5 is open and the ignition switch 2! will be rotated until the latch 25 rests upon the shunt switch and assumes the closed position. Then upon the establishment of combustion the stack mechanism rotates the shunt switch to closed position and the movement thereof will be imparted to the ignition switch and move it to the open position, as shown in Figure 3.

To hold the ignition switch in open position as long as the room thermostat remains closed, a portion of the carrying plate 22 is provided with a serrated arcuate portion 2i and an ignition switch latch is pivotally mounted between the plates 22a and 221) having a pawl 28 on one side of its pivot and a depending actuator arm 29 on the other side, the weight of which normally causes the pawl 28 to engage the serrations 2? at such an angle that the pawl will slide over the serrations as the ignition switch is rotated from closed to open position but, after the ignition switch is opened, will prevent movement in the opposite direction. To release the ignition switch to return to closed position when the room thermostat opens, the lower end of the actuator arm 29 is provided with a foot 30 extending toward the panel 9 and the movable coil 9 of the relay is provided with a latch arm in the form of a strip 3| carried on the upper side thereof and so arranged that when the room thermostat is closed and the relay energized,

the movement of the upper coil will carry the latch arm 3i out of the path of the foot 30 and allow the pawl 28 to. hold the ignition switch open, but as soon as the room thermostat opens and the coil 9 drops, the arm 30 will engage the foot 30 to trip the latch and release the pawl 28 to allow the ignition switch to close as the stack safety cools,

To prevent the relay upon being deenergized by any cause such as a quick manual opening and closing of the room thermostat or by an interruption in the commercial current, to open the motor switch and then again be energized to close the motor switch before the combustion chamber has cooled, a relay latch is provided to be engaged by the relay arm 3| when the coil 9 is in its lower or idle position to prevent upward movement thereof until contact with the latch hasbeen removed. To this end, the relay latch in the form of a plate 32 is secured at one end to a bushing 33 rotatably mounted upon the pivot 25- of the ignition switch carrying plate 22 and is extended in an arcuate latch member 3| serrated on the under side over the free end of the relay arm 3|, adapted under certain conditions to engage the end of the arm in the serrations and prevent upward movement of the coil 9. The stack safety mechanism illustrated is a commercial device constructed in accordance with this applicants prior Patent No. 1,762,183, dated June 10, 1930, and includes the curved plate 35 eccentrically movable with the plate 4 between the stops 35a and 35b. The relay latch plate 32 is provided with an extension which mounts a pin 38 extending over the upper portion of the plate 35 and so arranged when the parts are in idle or cold position, as shown in Figure 2, the plate 35 will engage the pin 36 and support the latch 34 out of contact with the arm 3|, but as the heat of combustion actuates the stack safety mechanism, the plate 35 is dropped to engage the stop 3511, which is the normal running position, allowing the latch member 34 to rest upon the free end of the relay arm 3|, as shown in Figure 3, so that as soon as the relay coil 9 drops, the end of the arm 3| is brought into engagement with the serrations on the under side of the latch 34 preventing upward movement of the coil 9 until the cooling of the combustion chamber returns the plate 35 to its cool position during which movement it engages the latch pin 36 and lifts the relay latch 34 to free the relay arm 3|. r

When the safety switch 1 has been opened by flame failure, a manual reset is necessary and there are times when it is desired to shut down during the normal running of the burner when it is not convenhent to do so by a manual operation of the thermostat. This invention contemplates a mounting for the safety switch, so that it may be manually released, and opened and closed by such' release means and at the same time prevent undue strain on the safety mechanism.

As shown in Figures 8 and 9, the safety switch 1 is mounted on a bracket l2 extending outward at right angles from the integral portion lZa mounted on the pivot 13. The switch carrying bracket terminates on a depending portion 12b parallel to the portion I la and mounts a man- "ual reset knurled knob 31 in alignment with the pivot I3. It is to be noted that the depending holding arm I1 is engaged by the pin l3 to hold the switch closed with the stop H on the plate In engaging the post l3. When the thermostatic strip l3 withdraws the pin |3, the weight of the switch I rotates its bracket until stop is thereon engages the post 16 and upon the cooling of the strip, the pin l3 will engage the body of the arm l1 under tension ofthe strip I93 so that a clockwise rotation of the knob 31 will rotate the arm .11 out of engagement-=and allow the pin l3 to assume the position shown in Figure 8'.

In order to effect a manual release of the switch 3, the pivot l3 of the bracket l2 is slidably mounted between the plates 23a and 23b and normally held in its normal position by a spring plate 33 mounted on the rear of plate 200, as shown in Figure 10, which allows the bracket when the knob 31 is depressed to slide back sufllciently to allow the arm l1 to be carried out of engagement with the pin l3 and upon a counterclockwisemovement of the knob 31 to be rotated to open the switch. To'prevent an attempted manual opening of, the switch, without first depressing the bracket, from placing an undue strain on the contact of the pin I3 and arm 11, the

knob 31 is pivotally mounted on the bracket,

ment is imparted to the knob 31, but engage the knob and bracket to move together when a clockwise movement is imparted to the knob 31. When the bracket is depressed to free the arm l1, a counterclockwise movement on the knob opens the switch, the tension of the spring pawl 31b being suflicient to cause the knob and bracket to rotate together.

Commercial controls for-electrically operated and controlled fluid fuel burners have employed heating elements to actuate a safety switch in the event of failure of ignition or flame failure during normal operation. For example, this applicants prior Patent No. 1,675,897, dated July 3, 1928, discloses a heating elementin series with a room thermostat and the commercial line. In the event of failure of ignition or flame failure thereafter, the commercial current passes through the heating element to release the motor switch, provided the commercial line current remains constant, but in the event of a voltage fluctuation downward, the heating element fails to function by either delaying the period for the motor switch to be opened or fails to open the motor switch altogether.

Other commercial controls have adapted the use of a safety mechanism including .a heating element for actuating the same which is connected in series with the load or a relay that controls the load or a magnetic oil valve without which fire cannot be established. This arrange-' ment provides protection against operation of theburner in the event the safety mechanism heating element is burned out. These controls usually employ stack temperature actuated mechanisms functioning upon establishment of combustion to shunt out the safety mechanism actuating element. However, with this type, assuming the relay or that which controls the load is a holding magnet of the clapper type, such as disclosed in this applicants prior Patent No. 1,884,045, dated October 25, 1932, which allowed for operation of the burner motor during normal periods of operation when the thermostat called for heat, it is possible for the control to permit uninterrupted operation of some burner motors upon a'very low drop in voltage even though conditions occur which should result in a shut down. The cause for such lack of protection lies in the fact that when holding magnets or relays are employed, even though they require considerable current for energization to attract the magnet armature,- after being closed the residual magnetism and the magnetic field established allows a considerable decrease in voltage below that required for initialenergization,before the release of the armature is effected. Thus in those instances where such voltage drops occur when the magnet is energized, that current passing through could cause a reduction in speed of the burner motor to render ineffective those ineans, controlled thereby, necessary for proper combustion. Therefore, the fire would become extinguished and while such a condition normally would result in a shut down, the current produced .by the voltage drop would be insumcient to actuate the safety switch mechanism and the motor would continue at a reduced speed to deliver oil without means to ignite it.

In still other commercial devices employing a low voltage control circuit, the safety mechanism heat element, magnet and thermostat are connected in series with the secondary of a transformer of the usual construction wherein the primary and secondary coils are maintained in fixed position with the output of the secondary a predetermined voltage. This construction permits the secondary voltage to vary in direct proportion with that in the primary and as the heat generated is directly proportional to the square of the current, it is possible to have a voltage drop in the primary which will produce a point in the secondary, below which the heat element will not actuate the safety mechanism.

The improvement disclosed in this invention contemplates the use of a transformer relay such as disclosed in the applicants pending application, Serial No. 500,747, filed December 8, 1930,

with the secondary thereof connected in series with the heat element and thermostat and makes possible the elimination of the customary holding magnet. As this relay is constructed there are points between the operating limits where the movable coil floats, and at these points, the relay is comparable to a constant current transformer, and the current remains substantially constant in the secondary upon decreases in voltage in the primary within the limits of the device. Consequently, as the normal operating position of the relay is with the movable coil at its upper most position, and the tripping time of the safety mechanism is set to trip a predetermined time after the passage of current therethrough with the coil in the repelled position, it is possible for the safety release to trip at lower line voltages, as long as the coil floats, without materially effecting the tripping time as set for the normally higher operating voltages.

This relay affords additional protection in that it is so designed that at abnormally low voltages upon initial energization the relay will not operate to close the motor circuit. This low voltage limit is established at that point in line voltage fluctuations where the current is not sufiicient to provide dependable motor operation. However, this low limit, at which point the relay opens the motor circuit, is reduced in the event such line voltage reductions occur after initial energization, but compared with the other types discussed, it is 50 percent higher than that point at which they break the motor circuit, and further, in the improved device, at these lower limits the movable coil still fioats and the safety mechanism remains operative. The reason for the point of motor circuit breaking, in the improved device, being lower after the circuit has once been closed is due to the use of a mercury tube switch as the circuit breaker which is actuated by the repulsion the movable coil. Therefore, having closed the circuit, the tube must be tilted through quite an angle before the mercury is caused to break the circuit therethrough.

To illustrate better the operating characteristics of the improved circuit control 'as compared with other types reference is made to Figure 11 in which a comparison is made to show the time required to actuate the safety mechanism at various voltages of the device herein disclosed, and those employing magnets in the manner heretofore described. The tests were conducted with the transformer relay or magnet placed in energized position so as to duplicate a field condition where the voltage drop occurred during the running of the burner. The tests were begun at 120 volts and then at each volt point below to'70 volts.

In the applicants commercial device, constructed in accordance with this invention, used in these tests, the motor switch was caused to close by energization of the relay at a line voltage of 85 volts, and thereafter, the opening of said switch was effected upon a drop to 62 volts. The other types of commercial devices, one of which was used in these tests, closed the motor switch at 91 volts'and maintained said switch closed until the voltage dropped to 43 volts, which has been shown in the foregoing discussion to result in hazardous conditions.

The disclosure made in this application has dealt with the adaptation of this improved timed circuit-breaker to a fluid fuel burning mechanism, principally because all of the advantages of the improved devices are utilized to provide the safety features essential to the operation of such heating mechanisms. However, wherever a remote controlled timed circuit breaker is desired through which equipment may be started, but stopped upon the failure of the equipment to function properly within a predetermined time after energizationfthis device may be adopted. While a temperature operated shunting mechanism has been disclosed to indicate proper functfoning' of the controlled equipment, it is readily seen that pressure, electrically, or mechanically operated shunt switching mechanisms may be employed as determined best suited or required of necessity by the type of equipment used.

The improved device disclosed in this applica tion comprises the transformer relay operated switch 6, shunting mechanism and the safety" switch mechanism, and by including the heatin element 2d of the safety switch mechanism in the secondary circuit of a repulsion transformer relay insures the operation of the safety switch at any and all times it may be required to operate including such times in which the relay circuit remains closed regardless of fluctuations or minimum line voltage.

In brief, this improved timed circuit breaker prevents motor operation below a predetermined low voltage; automatically checks this condition and restores operation when normal conditions again prevail; and above the predetermined low voltage operating point insures the functioning of the safety circuit breaker in the event of its needed operation, regardless of line voltage fluctuations through the operating range.

What I claim is:

l. A control system for an electrically operated motor including a source of electricity, a motor circuit, a motor switch in said circuit, means for operating the motor switch including a repulsion floating coil transformer relay having a stationary primary coil connected in parallel with the motor circuit, a control switch in the secondary circuit and means actuated by the floating of the secondary coil upon energization of the coils and a predetermined voltage being impressed upon the fixed coil upon the closing of the control switch to close the mot-or switch, a normally closed safety switch in the motor circuit, a thermally actuated safety switch release means including a heating element connected in series with the secondary circuit of the relay, a shunt circuit about" the heating element having a normally open shunt switch therein, and temperature responsive means for opening and closing said shunt switch, whereby while the motor switch remains closed and the shunt'switch remains open the floating coil of the relay upon voltage drops in the motor circuit self adjusts its repelled position throughout a predetermined range of voltage fluctuation in the primary coil to pass sufiicient current through the heating element to release the safety switch, said coil operating to open the motor circuit if the voltage falls below said range.

2. A control system for an electrically operated motor including a source of electricity, a motor circuit, a motor switch in said circuit, a normally closed safety switch in the motor circuit and a thermally actuated mechanism including an electric heating element adapted to release and open the safety switch a predetermined time after the passage of an electric current therethrough, a shunt circuit about the heating element, a normally open shunt switch in the shunt circuit, means to close and open the shunt switch, and a transformer relay having a stationary primary coil connected in series with the safety switch and in parallel with the motor circuit and a movable coil having a secondiry circuit connected in series With the safety switch heating element, a control switch in the secondary circuit and means actuated by the closing of the control switch to close the motor switch, said secondary coil assuming a repelled position upon energization of the transformer relay upon a predetermined voltage being impressed upon the fixed coil to actuate the closing of the motor switch and thereafter throughout a predetermined range of voltage fluctuations in the primary coil circuit the movable coil attains a self-adjusting repelled position which maintains the motor switch closed and in the event the shunt switch remains open to pass suflicient current through the heating element to release the safety switch to open the motor circuit, said coil operating to open; the motor circuit if the voltage falls below said range.

3. A control system for an electrically operated motor including a source of electricity, a motor circuit, a motor switch in said circuit, a normally closed safety switch in series with the motor circuit and a thermally actuated mechanism including an electric heating element adapted to release and open the safety switch a predetermined time after the passage of an.electric current therethrough, a shunt circuit about the heating ele ment, a normally open shunt switch, and a transformer relay having a stationary primary coil connected in series with the safety switch and in parallel with the motor circuit and a movable coil having a secondary circuit connected in series with the safety switch heating element, a control switch in the secondary circuit and means actuated by the closing of the control switch to close the motor switch, said secondary coil assuming a repelled position upon energization of the transformer relay upon a predetermined voltage being impressed upon the fixed coil to actuate the closing of the motor switch and thereafter throughout a predetermined range of voltage fluctuations in the primary coil circuit the movable coil attains a self-adjusting repelled position which maintains the motor switch closed and in the event the shunt switch remains open to pass sufficient current through the heating element to release the safety switch to open the motor and primary circuits, and upon failure of the voltage in the primary circuit to maintain said predetermined value, the secondary coil fails to assume said position and the motor switch is opened.

4. A timed circuit breaker system including a normally closed switch in the circuit to be controlled, a floating coil transformer relay having vice for said switch connected in series with the secondary circuit of the relay and means actuated by the floating coil of relay upon energization of the coils to maintain the circuit controlled by the relay closed through a predetermined voltage range impressed upon the controlled circuit and energize the timed tripping device sufficiently to be rendered effective within its operating time limit.

5. A control system for an electrically operated motor including a source of electricity, a motor circuit, a. motor switch in said circuit, a safety switch in the motor circuit, a transformer relay having relatively movable primary and secondary coils with the primary coil fixed and connected in series with the safety switch, a control switch in circuit with a secondary circuit of the movable coil, means actuated by the floating of the movable coil upon energization of the coils and a predetermined voltage being impressed upon the fixed coil to close the motor switch, a thermally actuated safety switch release mechanism including an electric heating element connected in series in the secondary circuit, a shunt switch in the secondary circuit adapted when closed to shunt out the heating element, and means for operating said shunt switch, said floating coil operable when the shunt switch is open to pass sufficient cur- 

